/*
 * Copyright 2004-2013 H2 Group. Multiple-Licensed under the H2 License,
 * Version 1.0, and under the Eclipse Public License, Version 1.0
 * (http://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */
package org.lealone.sql.expression.function;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.Connection;
import java.sql.Date;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Time;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Locale;
import java.util.TimeZone;
import java.util.regex.PatternSyntaxException;

import org.lealone.api.ErrorCode;
import org.lealone.common.compress.CompressTool;
import org.lealone.common.exceptions.DbException;
import org.lealone.common.security.BlockCipher;
import org.lealone.common.security.CipherFactory;
import org.lealone.common.security.SHA256;
import org.lealone.common.util.DataUtils;
import org.lealone.common.util.DateTimeUtils;
import org.lealone.common.util.JdbcUtils;
import org.lealone.common.util.MathUtils;
import org.lealone.common.util.New;
import org.lealone.common.util.StatementBuilder;
import org.lealone.common.util.StringUtils;
import org.lealone.common.util.Utils;
import org.lealone.db.Command;
import org.lealone.db.Constants;
import org.lealone.db.Csv;
import org.lealone.db.Database;
import org.lealone.db.Mode;
import org.lealone.db.ServerSession;
import org.lealone.db.expression.ExpressionVisitor;
import org.lealone.db.schema.Schema;
import org.lealone.db.schema.Sequence;
import org.lealone.db.service.ServiceExecuterManager;
import org.lealone.db.table.Column;
import org.lealone.db.table.ColumnResolver;
import org.lealone.db.table.Table;
import org.lealone.db.table.TableFilter;
import org.lealone.db.util.AutoCloseInputStream;
import org.lealone.db.value.DataType;
import org.lealone.db.value.Value;
import org.lealone.db.value.ValueArray;
import org.lealone.db.value.ValueBoolean;
import org.lealone.db.value.ValueBytes;
import org.lealone.db.value.ValueDate;
import org.lealone.db.value.ValueDouble;
import org.lealone.db.value.ValueInt;
import org.lealone.db.value.ValueLong;
import org.lealone.db.value.ValueNull;
import org.lealone.db.value.ValueResultSet;
import org.lealone.db.value.ValueString;
import org.lealone.db.value.ValueTime;
import org.lealone.db.value.ValueTimestamp;
import org.lealone.db.value.ValueUuid;
import org.lealone.sql.Parser;
import org.lealone.sql.expression.Expression;
import org.lealone.sql.expression.ExpressionColumn;
import org.lealone.sql.expression.SequenceValue;
import org.lealone.sql.expression.ValueExpression;
import org.lealone.sql.expression.Variable;
import org.lealone.storage.fs.FileUtils;

/**
 * This class implements most built-in functions of this database.
 */
public class Function extends Expression implements FunctionCall {
    public static final int ABS = 0, ACOS = 1, ASIN = 2, ATAN = 3, ATAN2 = 4, BITAND = 5, BITOR = 6, BITXOR = 7,
            CEILING = 8, COS = 9, COT = 10, DEGREES = 11, EXP = 12, FLOOR = 13, LOG = 14, LOG10 = 15, MOD = 16, PI = 17,
            POWER = 18, RADIANS = 19, RAND = 20, ROUND = 21, ROUNDMAGIC = 22, SIGN = 23, SIN = 24, SQRT = 25, TAN = 26,
            TRUNCATE = 27, SECURE_RAND = 28, HASH = 29, ENCRYPT = 30, DECRYPT = 31, COMPRESS = 32, EXPAND = 33,
            ZERO = 34, RANDOM_UUID = 35, COSH = 36, SINH = 37, TANH = 38, LN = 39;

    public static final int ASCII = 50, BIT_LENGTH = 51, CHAR = 52, CHAR_LENGTH = 53, CONCAT = 54, DIFFERENCE = 55,
            HEXTORAW = 56, INSERT = 57, INSTR = 58, LCASE = 59, LEFT = 60, LENGTH = 61, LOCATE = 62, LTRIM = 63,
            OCTET_LENGTH = 64, RAWTOHEX = 65, REPEAT = 66, REPLACE = 67, RIGHT = 68, RTRIM = 69, SOUNDEX = 70,
            SPACE = 71, SUBSTR = 72, SUBSTRING = 73, UCASE = 74, LOWER = 75, UPPER = 76, POSITION = 77, TRIM = 78,
            STRINGENCODE = 79, STRINGDECODE = 80, STRINGTOUTF8 = 81, UTF8TOSTRING = 82, XMLATTR = 83, XMLNODE = 84,
            XMLCOMMENT = 85, XMLCDATA = 86, XMLSTARTDOC = 87, XMLTEXT = 88, REGEXP_REPLACE = 89, RPAD = 90, LPAD = 91,
            CONCAT_WS = 92;

    public static final int CURDATE = 100, CURTIME = 101, DATE_ADD = 102, DATE_DIFF = 103, DAY_NAME = 104,
            DAY_OF_MONTH = 105, DAY_OF_WEEK = 106, DAY_OF_YEAR = 107, HOUR = 108, MINUTE = 109, MONTH = 110,
            MONTH_NAME = 111, NOW = 112, QUARTER = 113, SECOND = 114, WEEK = 115, YEAR = 116, CURRENT_DATE = 117,
            CURRENT_TIME = 118, CURRENT_TIMESTAMP = 119, EXTRACT = 120, FORMATDATETIME = 121, PARSEDATETIME = 122,
            ISO_YEAR = 123, ISO_WEEK = 124, ISO_DAY_OF_WEEK = 125;

    public static final int DATABASE = 150, USER = 151, CURRENT_USER = 152, IDENTITY = 153, SCOPE_IDENTITY = 154,
            AUTOCOMMIT = 155, READONLY = 156, DATABASE_PATH = 157, LOCK_TIMEOUT = 158, DISK_SPACE_USED = 159;

    public static final int IFNULL = 200, CASEWHEN = 201, CONVERT = 202, CAST = 203, COALESCE = 204, NULLIF = 205,
            CASE = 206, NEXTVAL = 207, CURRVAL = 208, ARRAY_GET = 209, CSVREAD = 210, CSVWRITE = 211, MEMORY_FREE = 212,
            MEMORY_USED = 213, LOCK_MODE = 214, SCHEMA = 215, SESSION_ID = 216, ARRAY_LENGTH = 217, LINK_SCHEMA = 218,
            GREATEST = 219, LEAST = 220, CANCEL_SESSION = 221, SET = 222, TABLE = 223, TABLE_DISTINCT = 224,
            FILE_READ = 225, TRANSACTION_ID = 226, TRUNCATE_VALUE = 227, NVL2 = 228, DECODE = 229, ARRAY_CONTAINS = 230;

    public static final int EXECUTE_SERVICE_NO_RETURN_VALUE = 500, EXECUTE_SERVICE_WITH_RETURN_VALUE = 501;

    /**
     * This is called LEALONE_VERSION() and not VERSION(), because we return a fake value
     * for VERSION() when running under the PostgreSQL ODBC driver.
     */
    public static final int LEALONE_VERSION = 231;

    public static final int ROW_NUMBER = 300;

    private static final int VAR_ARGS = -1;
    private static final long PRECISION_UNKNOWN = -1;

    private static final HashMap<String, FunctionInfo> FUNCTIONS = New.hashMap();
    private static final HashMap<String, Integer> DATE_PART = New.hashMap();
    private static final char[] SOUNDEX_INDEX = new char[128];

    protected Expression[] args;

    private final FunctionInfo info;
    private ArrayList<Expression> varArgs;
    private int dataType, scale;
    private long precision = PRECISION_UNKNOWN;
    private int displaySize;
    private final Database database;

    static {
        // DATE_PART
        DATE_PART.put("SQL_TSI_YEAR", Calendar.YEAR);
        DATE_PART.put("YEAR", Calendar.YEAR);
        DATE_PART.put("YYYY", Calendar.YEAR);
        DATE_PART.put("YY", Calendar.YEAR);
        DATE_PART.put("SQL_TSI_MONTH", Calendar.MONTH);
        DATE_PART.put("MONTH", Calendar.MONTH);
        DATE_PART.put("MM", Calendar.MONTH);
        DATE_PART.put("M", Calendar.MONTH);
        DATE_PART.put("SQL_TSI_WEEK", Calendar.WEEK_OF_YEAR);
        DATE_PART.put("WW", Calendar.WEEK_OF_YEAR);
        DATE_PART.put("WK", Calendar.WEEK_OF_YEAR);
        DATE_PART.put("WEEK", Calendar.WEEK_OF_YEAR);
        DATE_PART.put("DAY", Calendar.DAY_OF_MONTH);
        DATE_PART.put("DD", Calendar.DAY_OF_MONTH);
        DATE_PART.put("D", Calendar.DAY_OF_MONTH);
        DATE_PART.put("SQL_TSI_DAY", Calendar.DAY_OF_MONTH);
        DATE_PART.put("DAYOFYEAR", Calendar.DAY_OF_YEAR);
        DATE_PART.put("DAY_OF_YEAR", Calendar.DAY_OF_YEAR);
        DATE_PART.put("DY", Calendar.DAY_OF_YEAR);
        DATE_PART.put("DOY", Calendar.DAY_OF_YEAR);
        DATE_PART.put("SQL_TSI_HOUR", Calendar.HOUR_OF_DAY);
        DATE_PART.put("HOUR", Calendar.HOUR_OF_DAY);
        DATE_PART.put("HH", Calendar.HOUR_OF_DAY);
        DATE_PART.put("SQL_TSI_MINUTE", Calendar.MINUTE);
        DATE_PART.put("MINUTE", Calendar.MINUTE);
        DATE_PART.put("MI", Calendar.MINUTE);
        DATE_PART.put("N", Calendar.MINUTE);
        DATE_PART.put("SQL_TSI_SECOND", Calendar.SECOND);
        DATE_PART.put("SECOND", Calendar.SECOND);
        DATE_PART.put("SS", Calendar.SECOND);
        DATE_PART.put("S", Calendar.SECOND);
        DATE_PART.put("MILLISECOND", Calendar.MILLISECOND);
        DATE_PART.put("MS", Calendar.MILLISECOND);

        // SOUNDEX_INDEX
        String index = "7AEIOUY8HW1BFPV2CGJKQSXZ3DT4L5MN6R";
        char number = 0;
        for (int i = 0, length = index.length(); i < length; i++) {
            char c = index.charAt(i);
            if (c < '9') {
                number = c;
            } else {
                SOUNDEX_INDEX[c] = number;
                SOUNDEX_INDEX[Character.toLowerCase(c)] = number;
            }
        }

        // FUNCTIONS
        addFunction("ABS", ABS, 1, Value.NULL);
        addFunction("ACOS", ACOS, 1, Value.DOUBLE);
        addFunction("ASIN", ASIN, 1, Value.DOUBLE);
        addFunction("ATAN", ATAN, 1, Value.DOUBLE);
        addFunction("ATAN2", ATAN2, 2, Value.DOUBLE);
        addFunction("BITAND", BITAND, 2, Value.LONG);
        addFunction("BITOR", BITOR, 2, Value.LONG);
        addFunction("BITXOR", BITXOR, 2, Value.LONG);
        addFunction("CEILING", CEILING, 1, Value.DOUBLE);
        addFunction("CEIL", CEILING, 1, Value.DOUBLE);
        addFunction("COS", COS, 1, Value.DOUBLE);
        addFunction("COSH", COSH, 1, Value.DOUBLE);
        addFunction("COT", COT, 1, Value.DOUBLE);
        addFunction("DEGREES", DEGREES, 1, Value.DOUBLE);
        addFunction("EXP", EXP, 1, Value.DOUBLE);
        addFunction("FLOOR", FLOOR, 1, Value.DOUBLE);
        addFunction("LOG", LOG, 1, Value.DOUBLE);
        addFunction("LN", LN, 1, Value.DOUBLE);
        addFunction("LOG10", LOG10, 1, Value.DOUBLE);
        addFunction("MOD", MOD, 2, Value.LONG);
        addFunction("PI", PI, 0, Value.DOUBLE);
        addFunction("POWER", POWER, 2, Value.DOUBLE);
        addFunction("RADIANS", RADIANS, 1, Value.DOUBLE);
        // RAND without argument: get the next value
        // RAND with one argument: seed the random generator
        addFunctionNotDeterministic("RAND", RAND, VAR_ARGS, Value.DOUBLE);
        addFunctionNotDeterministic("RANDOM", RAND, VAR_ARGS, Value.DOUBLE);
        addFunction("ROUND", ROUND, VAR_ARGS, Value.DOUBLE);
        addFunction("ROUNDMAGIC", ROUNDMAGIC, 1, Value.DOUBLE);
        addFunction("SIGN", SIGN, 1, Value.INT);
        addFunction("SIN", SIN, 1, Value.DOUBLE);
        addFunction("SINH", SINH, 1, Value.DOUBLE);
        addFunction("SQRT", SQRT, 1, Value.DOUBLE);
        addFunction("TAN", TAN, 1, Value.DOUBLE);
        addFunction("TANH", TANH, 1, Value.DOUBLE);
        addFunction("TRUNCATE", TRUNCATE, VAR_ARGS, Value.NULL);
        // same as TRUNCATE
        addFunction("TRUNC", TRUNCATE, VAR_ARGS, Value.NULL);
        addFunction("HASH", HASH, 3, Value.BYTES);
        addFunction("ENCRYPT", ENCRYPT, 3, Value.BYTES);
        addFunction("DECRYPT", DECRYPT, 3, Value.BYTES);
        addFunctionNotDeterministic("SECURE_RAND", SECURE_RAND, 1, Value.BYTES);
        addFunction("COMPRESS", COMPRESS, VAR_ARGS, Value.BYTES);
        addFunction("EXPAND", EXPAND, 1, Value.BYTES);
        addFunction("ZERO", ZERO, 0, Value.INT);
        addFunctionNotDeterministic("RANDOM_UUID", RANDOM_UUID, 0, Value.UUID);
        addFunctionNotDeterministic("SYS_GUID", RANDOM_UUID, 0, Value.UUID);
        // string
        addFunction("ASCII", ASCII, 1, Value.INT);
        addFunction("BIT_LENGTH", BIT_LENGTH, 1, Value.LONG);
        addFunction("CHAR", CHAR, 1, Value.STRING);
        addFunction("CHR", CHAR, 1, Value.STRING);
        addFunction("CHAR_LENGTH", CHAR_LENGTH, 1, Value.INT);
        // same as CHAR_LENGTH
        addFunction("CHARACTER_LENGTH", CHAR_LENGTH, 1, Value.INT);
        addFunctionWithNull("CONCAT", CONCAT, VAR_ARGS, Value.STRING);
        addFunctionWithNull("CONCAT_WS", CONCAT_WS, VAR_ARGS, Value.STRING);
        addFunction("DIFFERENCE", DIFFERENCE, 2, Value.INT);
        addFunction("HEXTORAW", HEXTORAW, 1, Value.STRING);
        addFunctionWithNull("INSERT", INSERT, 4, Value.STRING);
        addFunction("LCASE", LCASE, 1, Value.STRING);
        addFunction("LEFT", LEFT, 2, Value.STRING);
        addFunction("LENGTH", LENGTH, 1, Value.LONG);
        // 2 or 3 arguments
        addFunction("LOCATE", LOCATE, VAR_ARGS, Value.INT);
        // alias for MSSQLServer
        addFunction("CHARINDEX", LOCATE, VAR_ARGS, Value.INT);
        // same as LOCATE with 2 arguments
        addFunction("POSITION", LOCATE, 2, Value.INT);
        addFunction("INSTR", INSTR, VAR_ARGS, Value.INT);
        addFunction("LTRIM", LTRIM, VAR_ARGS, Value.STRING);
        addFunction("OCTET_LENGTH", OCTET_LENGTH, 1, Value.LONG);
        addFunction("RAWTOHEX", RAWTOHEX, 1, Value.STRING);
        addFunction("REPEAT", REPEAT, 2, Value.STRING);
        addFunction("REPLACE", REPLACE, VAR_ARGS, Value.STRING);
        addFunction("RIGHT", RIGHT, 2, Value.STRING);
        addFunction("RTRIM", RTRIM, VAR_ARGS, Value.STRING);
        addFunction("SOUNDEX", SOUNDEX, 1, Value.STRING);
        addFunction("SPACE", SPACE, 1, Value.STRING);
        addFunction("SUBSTR", SUBSTR, VAR_ARGS, Value.STRING);
        addFunction("SUBSTRING", SUBSTRING, VAR_ARGS, Value.STRING);
        addFunction("UCASE", UCASE, 1, Value.STRING);
        addFunction("LOWER", LOWER, 1, Value.STRING);
        addFunction("UPPER", UPPER, 1, Value.STRING);
        addFunction("POSITION", POSITION, 2, Value.INT);
        addFunction("TRIM", TRIM, VAR_ARGS, Value.STRING);
        addFunction("STRINGENCODE", STRINGENCODE, 1, Value.STRING);
        addFunction("STRINGDECODE", STRINGDECODE, 1, Value.STRING);
        addFunction("STRINGTOUTF8", STRINGTOUTF8, 1, Value.BYTES);
        addFunction("UTF8TOSTRING", UTF8TOSTRING, 1, Value.STRING);
        addFunction("XMLATTR", XMLATTR, 2, Value.STRING);
        addFunctionWithNull("XMLNODE", XMLNODE, VAR_ARGS, Value.STRING);
        addFunction("XMLCOMMENT", XMLCOMMENT, 1, Value.STRING);
        addFunction("XMLCDATA", XMLCDATA, 1, Value.STRING);
        addFunction("XMLSTARTDOC", XMLSTARTDOC, 0, Value.STRING);
        addFunction("XMLTEXT", XMLTEXT, VAR_ARGS, Value.STRING);
        addFunction("REGEXP_REPLACE", REGEXP_REPLACE, 3, Value.STRING);
        addFunction("RPAD", RPAD, VAR_ARGS, Value.STRING);
        addFunction("LPAD", LPAD, VAR_ARGS, Value.STRING);

        // date
        addFunctionNotDeterministic("CURRENT_DATE", CURRENT_DATE, 0, Value.DATE);
        addFunctionNotDeterministic("CURDATE", CURDATE, 0, Value.DATE);
        // alias for MSSQLServer
        addFunctionNotDeterministic("GETDATE", CURDATE, 0, Value.DATE);
        addFunctionNotDeterministic("CURRENT_TIME", CURRENT_TIME, 0, Value.TIME);
        addFunctionNotDeterministic("CURTIME", CURTIME, 0, Value.TIME);
        addFunctionNotDeterministic("CURRENT_TIMESTAMP", CURRENT_TIMESTAMP, VAR_ARGS, Value.TIMESTAMP);
        addFunctionNotDeterministic("NOW", NOW, VAR_ARGS, Value.TIMESTAMP);
        addFunction("DATEADD", DATE_ADD, 3, Value.TIMESTAMP);
        addFunction("TIMESTAMPADD", DATE_ADD, 3, Value.LONG);
        addFunction("DATEDIFF", DATE_DIFF, 3, Value.LONG);
        addFunction("TIMESTAMPDIFF", DATE_DIFF, 3, Value.LONG);
        addFunction("DAYNAME", DAY_NAME, 1, Value.STRING);
        addFunction("DAYNAME", DAY_NAME, 1, Value.STRING);
        addFunction("DAY", DAY_OF_MONTH, 1, Value.INT);
        addFunction("DAY_OF_MONTH", DAY_OF_MONTH, 1, Value.INT);
        addFunction("DAY_OF_WEEK", DAY_OF_WEEK, 1, Value.INT);
        addFunction("DAY_OF_YEAR", DAY_OF_YEAR, 1, Value.INT);
        addFunction("DAYOFMONTH", DAY_OF_MONTH, 1, Value.INT);
        addFunction("DAYOFWEEK", DAY_OF_WEEK, 1, Value.INT);
        addFunction("DAYOFYEAR", DAY_OF_YEAR, 1, Value.INT);
        addFunction("HOUR", HOUR, 1, Value.INT);
        addFunction("MINUTE", MINUTE, 1, Value.INT);
        addFunction("MONTH", MONTH, 1, Value.INT);
        addFunction("MONTHNAME", MONTH_NAME, 1, Value.STRING);
        addFunction("QUARTER", QUARTER, 1, Value.INT);
        addFunction("SECOND", SECOND, 1, Value.INT);
        addFunction("WEEK", WEEK, 1, Value.INT);
        addFunction("YEAR", YEAR, 1, Value.INT);
        addFunction("EXTRACT", EXTRACT, 2, Value.INT);
        addFunctionWithNull("FORMATDATETIME", FORMATDATETIME, VAR_ARGS, Value.STRING);
        addFunctionWithNull("PARSEDATETIME", PARSEDATETIME, VAR_ARGS, Value.TIMESTAMP);
        addFunction("ISO_YEAR", ISO_YEAR, 1, Value.INT);
        addFunction("ISO_WEEK", ISO_WEEK, 1, Value.INT);
        addFunction("ISO_DAY_OF_WEEK", ISO_DAY_OF_WEEK, 1, Value.INT);
        // system
        addFunctionNotDeterministic("DATABASE", DATABASE, 0, Value.STRING);
        addFunctionNotDeterministic("USER", USER, 0, Value.STRING);
        addFunctionNotDeterministic("CURRENT_USER", CURRENT_USER, 0, Value.STRING);
        addFunctionNotDeterministic("IDENTITY", IDENTITY, 0, Value.LONG);
        addFunctionNotDeterministic("SCOPE_IDENTITY", SCOPE_IDENTITY, 0, Value.LONG);
        addFunctionNotDeterministic("IDENTITY_VAL_LOCAL", IDENTITY, 0, Value.LONG);
        addFunctionNotDeterministic("LAST_INSERT_ID", IDENTITY, 0, Value.LONG);
        addFunctionNotDeterministic("LASTVAL", IDENTITY, 0, Value.LONG);
        addFunctionNotDeterministic("AUTOCOMMIT", AUTOCOMMIT, 0, Value.BOOLEAN);
        addFunctionNotDeterministic("READONLY", READONLY, 0, Value.BOOLEAN);
        addFunction("DATABASE_PATH", DATABASE_PATH, 0, Value.STRING);
        addFunctionNotDeterministic("LOCK_TIMEOUT", LOCK_TIMEOUT, 0, Value.INT);
        addFunctionWithNull("IFNULL", IFNULL, 2, Value.NULL);
        addFunctionWithNull("ISNULL", IFNULL, 2, Value.NULL);
        addFunctionWithNull("CASEWHEN", CASEWHEN, 3, Value.NULL);
        addFunctionWithNull("CONVERT", CONVERT, 1, Value.NULL);
        addFunctionWithNull("CAST", CAST, 1, Value.NULL);
        addFunctionWithNull("TRUNCATE_VALUE", TRUNCATE_VALUE, 3, Value.NULL);
        addFunctionWithNull("COALESCE", COALESCE, VAR_ARGS, Value.NULL);
        addFunctionWithNull("NVL", COALESCE, VAR_ARGS, Value.NULL);
        addFunctionWithNull("NVL2", NVL2, 3, Value.NULL);
        addFunctionWithNull("NULLIF", NULLIF, 2, Value.NULL);
        addFunctionWithNull("CASE", CASE, VAR_ARGS, Value.NULL);
        addFunctionNotDeterministic("NEXTVAL", NEXTVAL, VAR_ARGS, Value.LONG);
        addFunctionNotDeterministic("CURRVAL", CURRVAL, VAR_ARGS, Value.LONG);
        addFunction("ARRAY_GET", ARRAY_GET, 2, Value.STRING);
        addFunction("ARRAY_CONTAINS", ARRAY_CONTAINS, 2, Value.BOOLEAN, false, true, false);
        addFunction("CSVREAD", CSVREAD, VAR_ARGS, Value.RESULT_SET, false, false, true);
        addFunction("CSVWRITE", CSVWRITE, VAR_ARGS, Value.INT, false, false, false);
        addFunctionNotDeterministic("MEMORY_FREE", MEMORY_FREE, 0, Value.INT);
        addFunctionNotDeterministic("MEMORY_USED", MEMORY_USED, 0, Value.INT);
        addFunctionNotDeterministic("LOCK_MODE", LOCK_MODE, 0, Value.INT);
        addFunctionNotDeterministic("SCHEMA", SCHEMA, 0, Value.STRING);
        addFunctionNotDeterministic("SESSION_ID", SESSION_ID, 0, Value.INT);
        addFunction("ARRAY_LENGTH", ARRAY_LENGTH, 1, Value.INT);
        addFunctionNotDeterministic("LINK_SCHEMA", LINK_SCHEMA, 6, Value.RESULT_SET);
        addFunctionWithNull("LEAST", LEAST, VAR_ARGS, Value.NULL);
        addFunctionWithNull("GREATEST", GREATEST, VAR_ARGS, Value.NULL);
        addFunctionNotDeterministic("CANCEL_SESSION", CANCEL_SESSION, 1, Value.BOOLEAN);
        addFunction("SET", SET, 2, Value.NULL, false, false, false);
        addFunction("FILE_READ", FILE_READ, VAR_ARGS, Value.NULL, false, false, false);
        addFunctionNotDeterministic("TRANSACTION_ID", TRANSACTION_ID, 0, Value.STRING);
        addFunctionWithNull("DECODE", DECODE, VAR_ARGS, Value.NULL);
        addFunctionNotDeterministic("DISK_SPACE_USED", DISK_SPACE_USED, 1, Value.LONG);
        addFunction("LEALONE_VERSION", LEALONE_VERSION, 0, Value.STRING);

        // TableFunction
        addFunctionWithNull("TABLE", TABLE, VAR_ARGS, Value.RESULT_SET);
        addFunctionWithNull("TABLE_DISTINCT", TABLE_DISTINCT, VAR_ARGS, Value.RESULT_SET);

        // pseudo function
        addFunctionWithNull("ROW_NUMBER", ROW_NUMBER, 0, Value.LONG);

        // service function
        addFunctionNotDeterministic("EXECUTE_SERVICE_NO_RETURN_VALUE", EXECUTE_SERVICE_NO_RETURN_VALUE, 2, Value.NULL);
        addFunctionNotDeterministic("EXECUTE_SERVICE_WITH_RETURN_VALUE", EXECUTE_SERVICE_WITH_RETURN_VALUE, 2,
                Value.STRING);
    }

    protected Function(Database database, FunctionInfo info) {
        this.database = database;
        this.info = info;
        if (info.parameterCount == VAR_ARGS) {
            varArgs = New.arrayList();
        } else {
            args = new Expression[info.parameterCount];
        }
    }

    private static void addFunction(String name, int type, int parameterCount, int dataType,
            boolean nullIfParameterIsNull, boolean deterministic, boolean bufferResultSetToLocalTemp) {
        FunctionInfo info = new FunctionInfo();
        info.name = name;
        info.type = type;
        info.parameterCount = parameterCount;
        info.dataType = dataType;
        info.nullIfParameterIsNull = nullIfParameterIsNull;
        info.deterministic = deterministic;
        info.bufferResultSetToLocalTemp = bufferResultSetToLocalTemp;
        FUNCTIONS.put(name, info);
    }

    private static void addFunctionNotDeterministic(String name, int type, int parameterCount, int dataType) {
        addFunction(name, type, parameterCount, dataType, true, false, false);
    }

    private static void addFunction(String name, int type, int parameterCount, int dataType) {
        addFunction(name, type, parameterCount, dataType, true, true, false);
    }

    private static void addFunctionWithNull(String name, int type, int parameterCount, int dataType) {
        addFunction(name, type, parameterCount, dataType, false, true, false);
    }

    /**
     * Get the function info object for this function, or null if there is no
     * such function.
     *
     * @param name the function name
     * @return the function info
     */
    private static FunctionInfo getFunctionInfo(String name) {
        return FUNCTIONS.get(name);
    }

    /**
     * Get an instance of the given function for this database.
     * If no function with this name is found, null is returned.
     *
     * @param database the database
     * @param name the function name
     * @return the function object or null
     */
    public static Function getFunction(Database database, String name) {
        if (!database.getSettings().databaseToUpper) {
            // if not yet converted to uppercase, do it now
            name = StringUtils.toUpperEnglish(name);
        }
        FunctionInfo info = getFunctionInfo(name);
        if (info == null) {
            return null;
        }
        switch (info.type) {
        case TABLE:
        case TABLE_DISTINCT:
            return new TableFunction(database, info, Long.MAX_VALUE);
        default:
            return new Function(database, info);
        }
    }

    /**
     * Set the parameter expression at the given index.
     *
     * @param index the index (0, 1,...)
     * @param param the expression
     */
    public void setParameter(int index, Expression param) {
        if (varArgs != null) {
            varArgs.add(param);
        } else {
            if (index >= args.length) {
                throw DbException.get(ErrorCode.INVALID_PARAMETER_COUNT_2, info.name, "" + args.length);
            }
            args[index] = param;
        }
    }

    private static strictfp double log10(double value) {
        return roundmagic(StrictMath.log(value) / StrictMath.log(10));
    }

    @Override
    public Value getValue(ServerSession session) {
        return getValueWithArgs(session, args);
    }

    private Value getSimpleValue(ServerSession session, Value v0, Expression[] args, Value[] values) {
        Value result;
        switch (info.type) {
        case ABS:
            result = v0.getSignum() > 0 ? v0 : v0.negate();
            break;
        case ACOS:
            result = ValueDouble.get(Math.acos(v0.getDouble()));
            break;
        case ASIN:
            result = ValueDouble.get(Math.asin(v0.getDouble()));
            break;
        case ATAN:
            result = ValueDouble.get(Math.atan(v0.getDouble()));
            break;
        case CEILING:
            result = ValueDouble.get(Math.ceil(v0.getDouble()));
            break;
        case COS:
            result = ValueDouble.get(Math.cos(v0.getDouble()));
            break;
        case COSH:
            result = ValueDouble.get(Math.cosh(v0.getDouble()));
            break;
        case COT: {
            double d = Math.tan(v0.getDouble());
            if (d == 0.0) {
                throw DbException.get(ErrorCode.DIVISION_BY_ZERO_1, getSQL());
            }
            result = ValueDouble.get(1. / d);
            break;
        }
        case DEGREES:
            result = ValueDouble.get(Math.toDegrees(v0.getDouble()));
            break;
        case EXP:
            result = ValueDouble.get(Math.exp(v0.getDouble()));
            break;
        case FLOOR:
            result = ValueDouble.get(Math.floor(v0.getDouble()));
            break;
        case LN:
            result = ValueDouble.get(Math.log(v0.getDouble()));
            break;
        case LOG:
            if (database.getMode().logIsLogBase10) {
                result = ValueDouble.get(Math.log10(v0.getDouble()));
            } else {
                result = ValueDouble.get(Math.log(v0.getDouble()));
            }
            break;
        case LOG10:
            result = ValueDouble.get(log10(v0.getDouble()));
            break;
        case PI:
            result = ValueDouble.get(Math.PI);
            break;
        case RADIANS:
            result = ValueDouble.get(Math.toRadians(v0.getDouble()));
            break;
        case RAND: {
            if (v0 != null) {
                session.getRandom().setSeed(v0.getInt());
            }
            result = ValueDouble.get(session.getRandom().nextDouble());
            break;
        }
        case ROUNDMAGIC:
            result = ValueDouble.get(roundmagic(v0.getDouble()));
            break;
        case SIGN:
            result = ValueInt.get(v0.getSignum());
            break;
        case SIN:
            result = ValueDouble.get(Math.sin(v0.getDouble()));
            break;
        case SINH:
            result = ValueDouble.get(Math.sinh(v0.getDouble()));
            break;
        case SQRT:
            result = ValueDouble.get(Math.sqrt(v0.getDouble()));
            break;
        case TAN:
            result = ValueDouble.get(Math.tan(v0.getDouble()));
            break;
        case TANH:
            result = ValueDouble.get(Math.tanh(v0.getDouble()));
            break;
        case SECURE_RAND:
            result = ValueBytes.getNoCopy(MathUtils.secureRandomBytes(v0.getInt()));
            break;
        case EXPAND:
            result = ValueBytes.getNoCopy(CompressTool.getInstance().expand(v0.getBytesNoCopy()));
            break;
        case ZERO:
            result = ValueInt.get(0);
            break;
        case RANDOM_UUID:
            result = ValueUuid.getNewRandom();
            break;
        // string
        case ASCII: {
            String s = v0.getString();
            if (s.length() == 0) {
                result = ValueNull.INSTANCE;
            } else {
                result = ValueInt.get(s.charAt(0));
            }
            break;
        }
        case BIT_LENGTH:
            result = ValueLong.get(16 * length(v0));
            break;
        case CHAR:
            result = ValueString.get(String.valueOf((char) v0.getInt()));
            break;
        case CHAR_LENGTH:
        case LENGTH:
            result = ValueLong.get(length(v0));
            break;
        case OCTET_LENGTH:
            result = ValueLong.get(2 * length(v0));
            break;
        case CONCAT_WS:
        case CONCAT: {
            result = ValueNull.INSTANCE;
            int start = 0;
            String separator = "";
            if (info.type == CONCAT_WS) {
                start = 1;
                separator = getNullOrValue(session, args, values, 0).getString();
            }
            for (int i = start; i < args.length; i++) {
                Value v = getNullOrValue(session, args, values, i);
                if (v == ValueNull.INSTANCE) {
                    continue;
                }
                if (result == ValueNull.INSTANCE) {
                    result = v;
                } else {
                    String tmp = v.getString();
                    if (!StringUtils.isNullOrEmpty(separator) && !StringUtils.isNullOrEmpty(tmp)) {
                        tmp = separator.concat(tmp);
                    }
                    result = ValueString.get(result.getString().concat(tmp));
                }
            }
            if (info.type == CONCAT_WS) {
                if (separator != null && result == ValueNull.INSTANCE) {
                    result = ValueString.get("");
                }
            }
            break;
        }
        case HEXTORAW:
            result = ValueString.get(hexToRaw(v0.getString()));
            break;
        case LOWER:
        case LCASE:
            // TODO this is locale specific, need to document or provide a way
            // to set the locale
            result = ValueString.get(v0.getString().toLowerCase());
            break;
        case RAWTOHEX:
            result = ValueString.get(rawToHex(v0.getString()));
            break;
        case SOUNDEX:
            result = ValueString.get(getSoundex(v0.getString()));
            break;
        case SPACE: {
            int len = Math.max(0, v0.getInt());
            char[] chars = new char[len];
            for (int i = len - 1; i >= 0; i--) {
                chars[i] = ' ';
            }
            result = ValueString.get(new String(chars));
            break;
        }
        case UPPER:
        case UCASE:
            // TODO this is locale specific, need to document or provide a way
            // to set the locale
            result = ValueString.get(v0.getString().toUpperCase());
            break;
        case STRINGENCODE:
            result = ValueString.get(StringUtils.javaEncode(v0.getString()));
            break;
        case STRINGDECODE:
            result = ValueString.get(StringUtils.javaDecode(v0.getString()));
            break;
        case STRINGTOUTF8:
            result = ValueBytes.getNoCopy(v0.getString().getBytes(Constants.UTF8));
            break;
        case UTF8TOSTRING:
            result = ValueString.get(new String(v0.getBytesNoCopy(), Constants.UTF8));
            break;
        case XMLCOMMENT:
            result = ValueString.get(StringUtils.xmlComment(v0.getString()));
            break;
        case XMLCDATA:
            result = ValueString.get(StringUtils.xmlCData(v0.getString()));
            break;
        case XMLSTARTDOC:
            result = ValueString.get(StringUtils.xmlStartDoc());
            break;
        case DAY_NAME: {
            SimpleDateFormat dayName = new SimpleDateFormat("EEEE", Locale.ENGLISH);
            result = ValueString.get(dayName.format(v0.getDate()));
            break;
        }
        case DAY_OF_MONTH:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.DAY_OF_MONTH));
            break;
        case DAY_OF_WEEK:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.DAY_OF_WEEK));
            break;
        case DAY_OF_YEAR:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.DAY_OF_YEAR));
            break;
        case HOUR:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getTimestamp(), Calendar.HOUR_OF_DAY));
            break;
        case MINUTE:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getTimestamp(), Calendar.MINUTE));
            break;
        case MONTH:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.MONTH));
            break;
        case MONTH_NAME: {
            SimpleDateFormat monthName = new SimpleDateFormat("MMMM", Locale.ENGLISH);
            result = ValueString.get(monthName.format(v0.getDate()));
            break;
        }
        case QUARTER:
            result = ValueInt.get((DateTimeUtils.getDatePart(v0.getDate(), Calendar.MONTH) - 1) / 3 + 1);
            break;
        case SECOND:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getTimestamp(), Calendar.SECOND));
            break;
        case WEEK:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.WEEK_OF_YEAR));
            break;
        case YEAR:
            result = ValueInt.get(DateTimeUtils.getDatePart(v0.getDate(), Calendar.YEAR));
            break;
        case ISO_YEAR:
            result = ValueInt.get(DateTimeUtils.getIsoYear(v0.getDate()));
            break;
        case ISO_WEEK:
            result = ValueInt.get(DateTimeUtils.getIsoWeek(v0.getDate()));
            break;
        case ISO_DAY_OF_WEEK:
            result = ValueInt.get(DateTimeUtils.getIsoDayOfWeek(v0.getDate()));
            break;
        case CURDATE:
        case CURRENT_DATE: {
            long now = session.getTransactionStart();
            // need to normalize
            result = ValueDate.get(new Date(now));
            break;
        }
        case CURTIME:
        case CURRENT_TIME: {
            long now = session.getTransactionStart();
            // need to normalize
            result = ValueTime.get(new Time(now));
            break;
        }
        case NOW:
        case CURRENT_TIMESTAMP: {
            long now = session.getTransactionStart();
            ValueTimestamp vt = ValueTimestamp.get(new Timestamp(now));
            if (v0 != null) {
                Mode mode = database.getMode();
                vt = (ValueTimestamp) vt.convertScale(mode.convertOnlyToSmallerScale, v0.getInt());
            }
            result = vt;
            break;
        }
        case DATABASE:
            result = ValueString.get(database.getShortName());
            break;
        case USER:
        case CURRENT_USER:
            result = ValueString.get(session.getUser().getName());
            break;
        case IDENTITY:
            result = session.getLastIdentity();
            break;
        case SCOPE_IDENTITY:
            result = session.getLastScopeIdentity();
            break;
        case AUTOCOMMIT:
            result = ValueBoolean.get(session.isAutoCommit());
            break;
        case READONLY:
            result = ValueBoolean.get(database.isReadOnly());
            break;
        case DATABASE_PATH: {
            String path = database.getDatabasePath();
            result = path == null ? (Value) ValueNull.INSTANCE : ValueString.get(path);
            break;
        }
        case LOCK_TIMEOUT:
            result = ValueInt.get(session.getLockTimeout());
            break;
        case DISK_SPACE_USED:
            result = ValueLong.get(getDiskSpaceUsed(session, v0));
            break;
        case CAST:
        case CONVERT: {
            v0 = v0.convertTo(dataType);
            Mode mode = database.getMode();
            v0 = v0.convertScale(mode.convertOnlyToSmallerScale, scale);
            v0 = v0.convertPrecision(getPrecision(), false);
            result = v0;
            break;
        }
        case MEMORY_FREE:
            session.getUser().checkAdmin();
            result = ValueInt.get(Utils.getMemoryFree());
            break;
        case MEMORY_USED:
            session.getUser().checkAdmin();
            result = ValueInt.get(Utils.getMemoryUsed());
            break;
        case LOCK_MODE:
            result = ValueInt.get(database.getLockMode());
            break;
        case SCHEMA:
            result = ValueString.get(session.getCurrentSchemaName());
            break;
        case SESSION_ID:
            result = ValueInt.get(session.getId());
            break;
        case IFNULL: {
            result = v0;
            if (v0 == ValueNull.INSTANCE) {
                result = getNullOrValue(session, args, values, 1);
            }
            break;
        }
        case CASEWHEN: {
            Value v;
            if (v0 == ValueNull.INSTANCE || !v0.getBoolean().booleanValue()) {
                v = getNullOrValue(session, args, values, 2);
            } else {
                v = getNullOrValue(session, args, values, 1);
            }
            result = v.convertTo(dataType);
            break;
        }
        case DECODE: {
            int index = -1;
            for (int i = 1; i < args.length - 1; i += 2) {
                if (database.areEqual(v0, getNullOrValue(session, args, values, i))) {
                    index = i + 1;
                }
            }
            if (index < 0 && args.length % 2 == 0) {
                index = args.length - 1;
            }
            Value v = index < 0 ? ValueNull.INSTANCE : getNullOrValue(session, args, values, index);
            result = v.convertTo(dataType);
            break;
        }
        case NVL2: {
            Value v;
            if (v0 == ValueNull.INSTANCE) {
                v = getNullOrValue(session, args, values, 2);
            } else {
                v = getNullOrValue(session, args, values, 1);
            }
            result = v.convertTo(dataType);
            break;
        }
        case COALESCE: {
            result = v0;
            for (int i = 0; i < args.length; i++) {
                Value v = getNullOrValue(session, args, values, i);
                if (!(v == ValueNull.INSTANCE)) {
                    result = v.convertTo(dataType);
                    break;
                }
            }
            break;
        }
        case GREATEST:
        case LEAST: {
            result = ValueNull.INSTANCE;
            for (int i = 0; i < args.length; i++) {
                Value v = getNullOrValue(session, args, values, i);
                if (!(v == ValueNull.INSTANCE)) {
                    v = v.convertTo(dataType);
                    if (result == ValueNull.INSTANCE) {
                        result = v;
                    } else {
                        int comp = database.compareTypeSafe(result, v);
                        if (info.type == GREATEST && comp < 0) {
                            result = v;
                        } else if (info.type == LEAST && comp > 0) {
                            result = v;
                        }
                    }
                }
            }
            break;
        }
        case CASE: {
            result = null;
            int i = 0;
            for (; i < args.length; i++) {
                Value when = getNullOrValue(session, args, values, i++);
                if (Boolean.TRUE.equals(when)) {
                    result = getNullOrValue(session, args, values, i);
                    break;
                }
            }
            if (result == null) {
                result = i < args.length ? getNullOrValue(session, args, values, i) : ValueNull.INSTANCE;
            }
            break;
        }
        case ARRAY_GET: {
            if (v0.getType() == Value.ARRAY) {
                Value v1 = getNullOrValue(session, args, values, 1);
                int element = v1.getInt();
                Value[] list = ((ValueArray) v0).getList();
                if (element < 1 || element > list.length) {
                    result = ValueNull.INSTANCE;
                } else {
                    result = list[element - 1];
                }
            } else {
                result = ValueNull.INSTANCE;
            }
            break;
        }
        case ARRAY_LENGTH: {
            if (v0.getType() == Value.ARRAY) {
                Value[] list = ((ValueArray) v0).getList();
                result = ValueInt.get(list.length);
            } else {
                result = ValueNull.INSTANCE;
            }
            break;
        }
        case ARRAY_CONTAINS: {
            result = ValueBoolean.get(false);
            if (v0.getType() == Value.ARRAY) {
                Value v1 = getNullOrValue(session, args, values, 1);
                Value[] list = ((ValueArray) v0).getList();
                for (Value v : list) {
                    if (v.equals(v1)) {
                        result = ValueBoolean.get(true);
                        break;
                    }
                }
            }
            break;
        }
        case CANCEL_SESSION: {
            result = ValueBoolean.get(cancelStatement(session, v0.getInt()));
            break;
        }
        case TRANSACTION_ID: {
            result = session.getTransactionId();
            break;
        }
        case EXECUTE_SERVICE_NO_RETURN_VALUE: {
            Value v1 = getNullOrValue(session, args, values, 1);
            ServiceExecuterManager.executeServiceNoReturnValue(v0.getString(), v1.getString());
            result = ValueNull.INSTANCE;
            break;
        }
        case EXECUTE_SERVICE_WITH_RETURN_VALUE: {
            Value v1 = getNullOrValue(session, args, values, 1);
            String r = ServiceExecuterManager.executeServiceWithReturnValue(v0.getString(), v1.getString());
            if (r == null)
                result = ValueNull.INSTANCE;
            else
                result = ValueString.get(r);
            break;
        }
        default:
            result = null;
        }
        return result;
    }

    private static boolean cancelStatement(ServerSession session, int targetSessionId) {
        session.getUser().checkAdmin();
        ServerSession[] sessions = session.getDatabase().getSessions(false);
        for (ServerSession s : sessions) {
            if (s.getId() == targetSessionId) {
                Command c = s.getCurrentCommand();
                if (c == null) {
                    return false;
                }
                c.cancel();
                return true;
            }
        }
        return false;
    }

    private static long getDiskSpaceUsed(ServerSession session, Value v0) {
        Parser p = new Parser(session);
        String sql = v0.getString();
        Table table = p.parseTableName(sql);
        return table.getDiskSpaceUsed();
    }

    private static Value getNullOrValue(ServerSession session, Expression[] args, Value[] values, int i) {
        if (i >= args.length) {
            return null;
        }
        Value v = values[i];
        if (v == null) {
            v = values[i] = args[i].getValue(session);
        }
        return v;
    }

    private Value getValueWithArgs(ServerSession session, Expression[] args) {
        Value[] values = new Value[args.length];
        if (info.nullIfParameterIsNull) {
            for (int i = 0; i < args.length; i++) {
                Expression e = args[i];
                Value v = e.getValue(session);
                if (v == ValueNull.INSTANCE) {
                    return ValueNull.INSTANCE;
                }
                values[i] = v;
            }
        }
        Value v0 = getNullOrValue(session, args, values, 0);
        Value resultSimple = getSimpleValue(session, v0, args, values);
        if (resultSimple != null) {
            return resultSimple;
        }
        Value v1 = getNullOrValue(session, args, values, 1);
        Value v2 = getNullOrValue(session, args, values, 2);
        Value v3 = getNullOrValue(session, args, values, 3);
        Value v4 = getNullOrValue(session, args, values, 4);
        Value v5 = getNullOrValue(session, args, values, 5);
        Value result;
        switch (info.type) {
        case ATAN2:
            result = ValueDouble.get(Math.atan2(v0.getDouble(), v1.getDouble()));
            break;
        case BITAND:
            result = ValueLong.get(v0.getLong() & v1.getLong());
            break;
        case BITOR:
            result = ValueLong.get(v0.getLong() | v1.getLong());
            break;
        case BITXOR:
            result = ValueLong.get(v0.getLong() ^ v1.getLong());
            break;
        case MOD: {
            long x = v1.getLong();
            if (x == 0) {
                throw DbException.get(ErrorCode.DIVISION_BY_ZERO_1, getSQL());
            }
            result = ValueLong.get(v0.getLong() % x);
            break;
        }
        case POWER:
            result = ValueDouble.get(Math.pow(v0.getDouble(), v1.getDouble()));
            break;
        case ROUND: {
            double f = v1 == null ? 1. : Math.pow(10., v1.getDouble());
            result = ValueDouble.get(Math.round(v0.getDouble() * f) / f);
            break;
        }
        case TRUNCATE: {
            if (v0.getType() == Value.TIMESTAMP) {
                java.sql.Timestamp d = v0.getTimestamp();
                Calendar c = Calendar.getInstance();
                c.setTime(d);
                c.set(Calendar.HOUR, 0);
                c.set(Calendar.MINUTE, 0);
                c.set(Calendar.SECOND, 0);
                c.set(Calendar.MILLISECOND, 0);
                result = ValueTimestamp.get(new java.sql.Timestamp(c.getTimeInMillis()));
            } else {
                double d = v0.getDouble();
                int p = v1.getInt();
                double f = Math.pow(10., p);
                double g = d * f;
                result = ValueDouble.get(((d < 0) ? Math.ceil(g) : Math.floor(g)) / f);
            }
            break;
        }
        case HASH:
            result = ValueBytes.getNoCopy(getHash(v0.getString(), v1.getBytesNoCopy(), v2.getInt()));
            break;
        case ENCRYPT:
            result = ValueBytes.getNoCopy(encrypt(v0.getString(), v1.getBytesNoCopy(), v2.getBytesNoCopy()));
            break;
        case DECRYPT:
            result = ValueBytes.getNoCopy(decrypt(v0.getString(), v1.getBytesNoCopy(), v2.getBytesNoCopy()));
            break;
        case COMPRESS: {
            String algorithm = null;
            if (v1 != null) {
                algorithm = v1.getString();
            }
            result = ValueBytes.getNoCopy(CompressTool.getInstance().compress(v0.getBytesNoCopy(), algorithm));
            break;
        }
        case DIFFERENCE:
            result = ValueInt.get(getDifference(v0.getString(), v1.getString()));
            break;
        case INSERT: {
            if (v1 == ValueNull.INSTANCE || v2 == ValueNull.INSTANCE) {
                result = v1;
            } else {
                result = ValueString.get(insert(v0.getString(), v1.getInt(), v2.getInt(), v3.getString()));
            }
            break;
        }
        case LEFT:
            result = ValueString.get(left(v0.getString(), v1.getInt()));
            break;
        case LOCATE: {
            int start = v2 == null ? 0 : v2.getInt();
            result = ValueInt.get(locate(v0.getString(), v1.getString(), start));
            break;
        }
        case INSTR: {
            int start = v2 == null ? 0 : v2.getInt();
            result = ValueInt.get(locate(v1.getString(), v0.getString(), start));
            break;
        }
        case REPEAT: {
            int count = Math.max(0, v1.getInt());
            result = ValueString.get(repeat(v0.getString(), count));
            break;
        }
        case REPLACE: {
            String s0 = v0.getString();
            String s1 = v1.getString();
            String s2 = (v2 == null) ? "" : v2.getString();
            result = ValueString.get(replace(s0, s1, s2));
            break;
        }
        case RIGHT:
            result = ValueString.get(right(v0.getString(), v1.getInt()));
            break;
        case LTRIM:
            result = ValueString.get(StringUtils.trim(v0.getString(), true, false, v1 == null ? " " : v1.getString()));
            break;
        case TRIM:
            result = ValueString.get(StringUtils.trim(v0.getString(), true, true, v1 == null ? " " : v1.getString()));
            break;
        case RTRIM:
            result = ValueString.get(StringUtils.trim(v0.getString(), false, true, v1 == null ? " " : v1.getString()));
            break;
        case SUBSTR:
        case SUBSTRING: {
            String s = v0.getString();
            int offset = v1.getInt();
            if (offset < 0) {
                offset = s.length() + offset + 1;
            }
            int length = v2 == null ? s.length() : v2.getInt();
            result = ValueString.get(substring(s, offset, length));
            break;
        }
        case POSITION:
            result = ValueInt.get(locate(v0.getString(), v1.getString(), 0));
            break;
        case XMLATTR:
            result = ValueString.get(StringUtils.xmlAttr(v0.getString(), v1.getString()));
            break;
        case XMLNODE: {
            String attr = v1 == null ? null : v1 == ValueNull.INSTANCE ? null : v1.getString();
            String content = v2 == null ? null : v2 == ValueNull.INSTANCE ? null : v2.getString();
            boolean indent = v3 == null ? true : v3.getBoolean();
            result = ValueString.get(StringUtils.xmlNode(v0.getString(), attr, content, indent));
            break;
        }
        case REGEXP_REPLACE: {
            String regexp = v1.getString();
            try {
                result = ValueString.get(v0.getString().replaceAll(regexp, v2.getString()));
            } catch (PatternSyntaxException e) {
                throw DbException.get(ErrorCode.LIKE_ESCAPE_ERROR_1, e, regexp);
            }
            break;
        }
        case RPAD:
            result = ValueString
                    .get(StringUtils.pad(v0.getString(), v1.getInt(), v2 == null ? null : v2.getString(), true));
            break;
        case LPAD:
            result = ValueString
                    .get(StringUtils.pad(v0.getString(), v1.getInt(), v2 == null ? null : v2.getString(), false));
            break;
        case LEALONE_VERSION:
            result = ValueString.get(Constants.getVersion());
            break;
        // date
        case DATE_ADD:
            result = ValueTimestamp.get(dateadd(v0.getString(), v1.getInt(), v2.getTimestamp()));
            break;
        case DATE_DIFF:
            result = ValueLong.get(datediff(v0.getString(), v1.getTimestamp(), v2.getTimestamp()));
            break;
        case EXTRACT: {
            int field = getDatePart(v0.getString());
            result = ValueInt.get(DateTimeUtils.getDatePart(v1.getTimestamp(), field));
            break;
        }
        case FORMATDATETIME: {
            if (v0 == ValueNull.INSTANCE || v1 == ValueNull.INSTANCE) {
                result = ValueNull.INSTANCE;
            } else {
                String locale = v2 == null ? null : v2 == ValueNull.INSTANCE ? null : v2.getString();
                String tz = v3 == null ? null : v3 == ValueNull.INSTANCE ? null : v3.getString();
                result = ValueString.get(DateTimeUtils.formatDateTime(v0.getTimestamp(), v1.getString(), locale, tz));
            }
            break;
        }
        case PARSEDATETIME: {
            if (v0 == ValueNull.INSTANCE || v1 == ValueNull.INSTANCE) {
                result = ValueNull.INSTANCE;
            } else {
                String locale = v2 == null ? null : v2 == ValueNull.INSTANCE ? null : v2.getString();
                String tz = v3 == null ? null : v3 == ValueNull.INSTANCE ? null : v3.getString();
                java.util.Date d = DateTimeUtils.parseDateTime(v0.getString(), v1.getString(), locale, tz);
                result = ValueTimestamp.get(new Timestamp(d.getTime()));
            }
            break;
        }
        case NULLIF:
            result = database.areEqual(v0, v1) ? ValueNull.INSTANCE : v0;
            break;
        // system
        case NEXTVAL: {
            Sequence sequence = getSequence(session, v0, v1);
            SequenceValue value = new SequenceValue(sequence);
            result = value.getValue(session);
            break;
        }
        case CURRVAL: {
            Sequence sequence = getSequence(session, v0, v1);
            result = ValueLong.get(sequence.getCurrentValue());
            break;
        }
        case CSVREAD: {
            String fileName = v0.getString();
            String columnList = v1 == null ? null : v1.getString();
            Csv csv = new Csv();
            String options = v2 == null ? null : v2.getString();
            String charset = null;
            if (options != null && options.indexOf('=') >= 0) {
                charset = csv.setOptions(options);
            } else {
                charset = options;
                String fieldSeparatorRead = v3 == null ? null : v3.getString();
                String fieldDelimiter = v4 == null ? null : v4.getString();
                String escapeCharacter = v5 == null ? null : v5.getString();
                Value v6 = getNullOrValue(session, args, values, 6);
                String nullString = v6 == null ? null : v6.getString();
                setCsvDelimiterEscape(csv, fieldSeparatorRead, fieldDelimiter, escapeCharacter);
                csv.setNullString(nullString);
            }
            char fieldSeparator = csv.getFieldSeparatorRead();
            String[] columns = StringUtils.arraySplit(columnList, fieldSeparator, true);
            try {
                ValueResultSet vr = ValueResultSet.get(csv.read(fileName, columns, charset));
                result = vr;
            } catch (SQLException e) {
                throw DbException.convert(e);
            }
            break;
        }
        case LINK_SCHEMA: {
            // session.getUser().checkAdmin();
            // Connection conn = session.createConnection(false);
            // ResultSet rs = LinkSchema.linkSchema(conn, v0.getString(), v1.getString(), v2.getString(),
            // v3.getString(),
            // v4.getString(), v5.getString());
            // result = ValueResultSet.get(rs);

            throw DbException.getUnsupportedException("LINK_SCHEMA");
        }
        case CSVWRITE: {
            session.getUser().checkAdmin();
            Connection conn = session.createConnection(false);
            Csv csv = new Csv();
            String options = v2 == null ? null : v2.getString();
            String charset = null;
            if (options != null && options.indexOf('=') >= 0) {
                charset = csv.setOptions(options);
            } else {
                charset = options;
                String fieldSeparatorWrite = v3 == null ? null : v3.getString();
                String fieldDelimiter = v4 == null ? null : v4.getString();
                String escapeCharacter = v5 == null ? null : v5.getString();
                Value v6 = getNullOrValue(session, args, values, 6);
                String nullString = v6 == null ? null : v6.getString();
                Value v7 = getNullOrValue(session, args, values, 7);
                String lineSeparator = v7 == null ? null : v7.getString();
                setCsvDelimiterEscape(csv, fieldSeparatorWrite, fieldDelimiter, escapeCharacter);
                csv.setNullString(nullString);
                if (lineSeparator != null) {
                    csv.setLineSeparator(lineSeparator);
                }
            }
            try {
                int rows = csv.write(conn, v0.getString(), v1.getString(), charset);
                result = ValueInt.get(rows);
            } catch (SQLException e) {
                throw DbException.convert(e);
            }
            break;
        }
        case SET: {
            Variable var = (Variable) args[0];
            session.setVariable(var.getName(), v1);
            result = v1;
            break;
        }
        case FILE_READ: {
            session.getUser().checkAdmin();
            String fileName = v0.getString();
            boolean blob = args.length == 1;
            try {
                InputStream in = new AutoCloseInputStream(FileUtils.newInputStream(fileName));
                if (blob) {
                    result = database.getLobStorage().createBlob(in, -1);
                } else {
                    Reader reader;
                    if (v1 == ValueNull.INSTANCE) {
                        reader = new InputStreamReader(in);
                    } else {
                        reader = new InputStreamReader(in, v1.getString());
                    }
                    result = database.getLobStorage().createClob(reader, -1);
                }
            } catch (IOException e) {
                throw DbException.convertIOException(e, fileName);
            }
            break;
        }
        case TRUNCATE_VALUE: {
            result = v0.convertPrecision(v1.getLong(), v2.getBoolean());
            break;
        }
        case XMLTEXT:
            if (v1 == null) {
                result = ValueString.get(StringUtils.xmlText(v0.getString()));
            } else {
                result = ValueString.get(StringUtils.xmlText(v0.getString(), v1.getBoolean()));
            }
            break;
        default:
            throw DbException.throwInternalError("type=" + info.type);
        }
        return result;
    }

    private Sequence getSequence(ServerSession session, Value v0, Value v1) {
        String schemaName, sequenceName;
        if (v1 == null) {
            Parser p = (Parser) session.getParser();
            String sql = v0.getString();
            Expression expr = p.parseExpression(sql);
            if (expr instanceof ExpressionColumn) {
                ExpressionColumn seq = (ExpressionColumn) expr;
                schemaName = seq.getOriginalTableAliasName();
                if (schemaName == null) {
                    schemaName = session.getCurrentSchemaName();
                    sequenceName = sql;
                } else {
                    sequenceName = seq.getColumnName();
                }
            } else {
                throw DbException.getSyntaxError(sql, 1);
            }
        } else {
            schemaName = v0.getString();
            sequenceName = v1.getString();
        }
        Schema s = database.findSchema(schemaName);
        if (s == null) {
            schemaName = StringUtils.toUpperEnglish(schemaName);
            s = database.getSchema(schemaName);
        }
        Sequence seq = s.findSequence(sequenceName);
        if (seq == null) {
            sequenceName = StringUtils.toUpperEnglish(sequenceName);
            seq = s.getSequence(sequenceName);
        }
        return seq;
    }

    private static long length(Value v) {
        switch (v.getType()) {
        case Value.BLOB:
        case Value.CLOB:
        case Value.BYTES:
        case Value.JAVA_OBJECT:
            return v.getPrecision();
        default:
            return v.getString().length();
        }
    }

    private static byte[] getPaddedArrayCopy(byte[] data, int blockSize) {
        int size = MathUtils.roundUpInt(data.length, blockSize);
        byte[] newData = DataUtils.newBytes(size);
        System.arraycopy(data, 0, newData, 0, data.length);
        return newData;
    }

    private static byte[] decrypt(String algorithm, byte[] key, byte[] data) {
        BlockCipher cipher = CipherFactory.getBlockCipher(algorithm);
        byte[] newKey = getPaddedArrayCopy(key, cipher.getKeyLength());
        cipher.setKey(newKey);
        byte[] newData = getPaddedArrayCopy(data, BlockCipher.ALIGN);
        cipher.decrypt(newData, 0, newData.length);
        return newData;
    }

    private static byte[] encrypt(String algorithm, byte[] key, byte[] data) {
        BlockCipher cipher = CipherFactory.getBlockCipher(algorithm);
        byte[] newKey = getPaddedArrayCopy(key, cipher.getKeyLength());
        cipher.setKey(newKey);
        byte[] newData = getPaddedArrayCopy(data, BlockCipher.ALIGN);
        cipher.encrypt(newData, 0, newData.length);
        return newData;
    }

    private static byte[] getHash(String algorithm, byte[] bytes, int iterations) {
        if (!"SHA256".equalsIgnoreCase(algorithm)) {
            throw DbException.getInvalidValueException("algorithm", algorithm);
        }
        for (int i = 0; i < iterations; i++) {
            bytes = SHA256.getHash(bytes, false);
        }
        return bytes;
    }

    /**
     * Check if a given string is a valid date part string.
     *
     * @param part the string
     * @return true if it is
     */
    public static boolean isDatePart(String part) {
        Integer p = DATE_PART.get(StringUtils.toUpperEnglish(part));
        return p != null;
    }

    private static int getDatePart(String part) {
        Integer p = DATE_PART.get(StringUtils.toUpperEnglish(part));
        if (p == null) {
            throw DbException.getInvalidValueException("date part", part);
        }
        return p.intValue();
    }

    private static Timestamp dateadd(String part, int count, Timestamp d) {
        int field = getDatePart(part);
        Calendar calendar = Calendar.getInstance();
        int nanos = d.getNanos() % 1000000;
        calendar.setTime(d);
        calendar.add(field, count);
        long t = calendar.getTime().getTime();
        Timestamp ts = new Timestamp(t);
        ts.setNanos(ts.getNanos() + nanos);
        return ts;
    }

    /**
     * Calculate the number of crossed unit boundaries between two timestamps.
     * This method is supported for MS SQL Server compatibility.
     * <pre>
     * DATEDIFF(YEAR, '2004-12-31', '2005-01-01') = 1
     * </pre>
     *
     * @param part the part
     * @param d1 the first date
     * @param d2 the second date
     * @return the number of crossed boundaries
     */
    private static long datediff(String part, Timestamp d1, Timestamp d2) {
        int field = getDatePart(part);
        Calendar calendar = Calendar.getInstance();
        long t1 = d1.getTime(), t2 = d2.getTime();
        // need to convert to UTC, otherwise we get inconsistent results with
        // certain time zones (those that are 30 minutes off)
        TimeZone zone = calendar.getTimeZone();
        calendar.setTime(d1);
        t1 += zone.getOffset(calendar.get(Calendar.ERA), calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH), calendar.get(Calendar.DAY_OF_WEEK),
                calendar.get(Calendar.MILLISECOND));
        calendar.setTime(d2);
        t2 += zone.getOffset(calendar.get(Calendar.ERA), calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH), calendar.get(Calendar.DAY_OF_WEEK),
                calendar.get(Calendar.MILLISECOND));
        switch (field) {
        case Calendar.MILLISECOND:
            return t2 - t1;
        case Calendar.SECOND:
        case Calendar.MINUTE:
        case Calendar.HOUR_OF_DAY: {
            // first 'normalize' the numbers so both are not negative
            long hour = 60 * 60 * 1000;
            long add = Math.min(t1 / hour * hour, t2 / hour * hour);
            t1 -= add;
            t2 -= add;
            switch (field) {
            case Calendar.SECOND:
                return t2 / 1000 - t1 / 1000;
            case Calendar.MINUTE:
                return t2 / (60 * 1000) - t1 / (60 * 1000);
            case Calendar.HOUR_OF_DAY:
                return t2 / hour - t1 / hour;
            default:
                throw DbException.throwInternalError("field:" + field);
            }
        }
        case Calendar.DATE:
            return t2 / (24 * 60 * 60 * 1000) - t1 / (24 * 60 * 60 * 1000);
        default:
            break;
        }
        calendar.setTime(new Timestamp(t1));
        int year1 = calendar.get(Calendar.YEAR);
        int month1 = calendar.get(Calendar.MONTH);
        calendar.setTime(new Timestamp(t2));
        int year2 = calendar.get(Calendar.YEAR);
        int month2 = calendar.get(Calendar.MONTH);
        int result = year2 - year1;
        if (field == Calendar.MONTH) {
            result = 12 * result + (month2 - month1);
        }
        return result;
    }

    private static String substring(String s, int start, int length) {
        int len = s.length();
        start--;
        if (start < 0) {
            start = 0;
        }
        if (length < 0) {
            length = 0;
        }
        start = (start > len) ? len : start;
        if (start + length > len) {
            length = len - start;
        }
        return s.substring(start, start + length);
    }

    private static String replace(String s, String replace, String with) {
        if (s == null || replace == null || with == null) {
            return null;
        }
        if (replace.length() == 0) {
            // avoid out of memory
            return s;
        }
        StringBuilder buff = new StringBuilder(s.length());
        int start = 0;
        int len = replace.length();
        while (true) {
            int i = s.indexOf(replace, start);
            if (i == -1) {
                break;
            }
            buff.append(s.substring(start, i)).append(with);
            start = i + len;
        }
        buff.append(s.substring(start));
        return buff.toString();
    }

    private static String repeat(String s, int count) {
        StringBuilder buff = new StringBuilder(s.length() * count);
        while (count-- > 0) {
            buff.append(s);
        }
        return buff.toString();
    }

    private static String rawToHex(String s) {
        int length = s.length();
        StringBuilder buff = new StringBuilder(4 * length);
        for (int i = 0; i < length; i++) {
            String hex = Integer.toHexString(s.charAt(i) & 0xffff);
            for (int j = hex.length(); j < 4; j++) {
                buff.append('0');
            }
            buff.append(hex);
        }
        return buff.toString();
    }

    private static int locate(String search, String s, int start) {
        if (start < 0) {
            int i = s.length() + start;
            return s.lastIndexOf(search, i) + 1;
        }
        int i = (start == 0) ? 0 : start - 1;
        return s.indexOf(search, i) + 1;
    }

    private static String right(String s, int count) {
        if (count < 0) {
            count = 0;
        } else if (count > s.length()) {
            count = s.length();
        }
        return s.substring(s.length() - count);
    }

    private static String left(String s, int count) {
        if (count < 0) {
            count = 0;
        } else if (count > s.length()) {
            count = s.length();
        }
        return s.substring(0, count);
    }

    private static String insert(String s1, int start, int length, String s2) {
        if (s1 == null) {
            return s2;
        }
        if (s2 == null) {
            return s1;
        }
        int len1 = s1.length();
        int len2 = s2.length();
        start--;
        if (start < 0 || length <= 0 || len2 == 0 || start > len1) {
            return s1;
        }
        if (start + length > len1) {
            length = len1 - start;
        }
        return s1.substring(0, start) + s2 + s1.substring(start + length);
    }

    private static String hexToRaw(String s) {
        // TODO function hextoraw compatibility with oracle
        int len = s.length();
        if (len % 4 != 0) {
            throw DbException.get(ErrorCode.DATA_CONVERSION_ERROR_1, s);
        }
        StringBuilder buff = new StringBuilder(len / 4);
        for (int i = 0; i < len; i += 4) {
            try {
                char raw = (char) Integer.parseInt(s.substring(i, i + 4), 16);
                buff.append(raw);
            } catch (NumberFormatException e) {
                throw DbException.get(ErrorCode.DATA_CONVERSION_ERROR_1, s);
            }
        }
        return buff.toString();
    }

    private static int getDifference(String s1, String s2) {
        // TODO function difference: compatibility with SQL Server and HSQLDB
        s1 = getSoundex(s1);
        s2 = getSoundex(s2);
        int e = 0;
        for (int i = 0; i < 4; i++) {
            if (s1.charAt(i) == s2.charAt(i)) {
                e++;
            }
        }
        return e;
    }

    private static double roundmagic(double d) {
        if ((d < 0.0000000000001) && (d > -0.0000000000001)) {
            return 0.0;
        }
        if ((d > 1000000000000.) || (d < -1000000000000.)) {
            return d;
        }
        StringBuilder s = new StringBuilder();
        s.append(d);
        if (s.toString().indexOf("E") >= 0) {
            return d;
        }
        int len = s.length();
        if (len < 16) {
            return d;
        }
        if (s.toString().indexOf(".") > len - 3) {
            return d;
        }
        s.delete(len - 2, len);
        len -= 2;
        char c1 = s.charAt(len - 2);
        char c2 = s.charAt(len - 3);
        char c3 = s.charAt(len - 4);
        if ((c1 == '0') && (c2 == '0') && (c3 == '0')) {
            s.setCharAt(len - 1, '0');
        } else if ((c1 == '9') && (c2 == '9') && (c3 == '9')) {
            s.setCharAt(len - 1, '9');
            s.append('9');
            s.append('9');
            s.append('9');
        }
        return Double.parseDouble(s.toString());
    }

    private static String getSoundex(String s) {
        int len = s.length();
        char[] chars = { '0', '0', '0', '0' };
        char lastDigit = '0';
        for (int i = 0, j = 0; i < len && j < 4; i++) {
            char c = s.charAt(i);
            char newDigit = c > SOUNDEX_INDEX.length ? 0 : SOUNDEX_INDEX[c];
            if (newDigit != 0) {
                if (j == 0) {
                    chars[j++] = c;
                    lastDigit = newDigit;
                } else if (newDigit <= '6') {
                    if (newDigit != lastDigit) {
                        chars[j++] = newDigit;
                        lastDigit = newDigit;
                    }
                } else if (newDigit == '7') {
                    lastDigit = newDigit;
                }
            }
        }
        return new String(chars);
    }

    @Override
    public int getType() {
        return dataType;
    }

    @Override
    public void mapColumns(ColumnResolver resolver, int level) {
        for (Expression e : args) {
            e.mapColumns(resolver, level);
        }
    }

    /**
     * Check if the parameter count is correct.
     *
     * @param len the number of parameters set
     * @throws DbException if the parameter count is incorrect
     */
    protected void checkParameterCount(int len) {
        int min = 0, max = Integer.MAX_VALUE;
        switch (info.type) {
        case COALESCE:
        case CSVREAD:
        case LEAST:
        case GREATEST:
            min = 1;
            break;
        case NOW:
        case CURRENT_TIMESTAMP:
        case RAND:
            max = 1;
            break;
        case COMPRESS:
        case LTRIM:
        case RTRIM:
        case TRIM:
        case FILE_READ:
        case ROUND:
        case XMLTEXT:
        case TRUNCATE:
            min = 1;
            max = 2;
            break;
        case REPLACE:
        case LOCATE:
        case INSTR:
        case SUBSTR:
        case SUBSTRING:
        case LPAD:
        case RPAD:
            min = 2;
            max = 3;
            break;
        case CASE:
        case CONCAT:
        case CONCAT_WS:
        case CSVWRITE:
            min = 2;
            break;
        case XMLNODE:
            min = 1;
            max = 4;
            break;
        case FORMATDATETIME:
        case PARSEDATETIME:
            min = 2;
            max = 4;
            break;
        case CURRVAL:
        case NEXTVAL:
            min = 1;
            max = 2;
            break;
        case DECODE:
            min = 3;
            break;
        default:
            DbException.throwInternalError("type=" + info.type);
        }
        boolean ok = (len >= min) && (len <= max);
        if (!ok) {
            throw DbException.get(ErrorCode.INVALID_PARAMETER_COUNT_2, info.name, min + ".." + max);
        }
    }

    /**
     * This method is called after all the parameters have been set.
     * It checks if the parameter count is correct.
     *
     * @throws DbException if the parameter count is incorrect.
     */
    public void doneWithParameters() {
        if (info.parameterCount == VAR_ARGS) {
            int len = varArgs.size();
            checkParameterCount(len);
            args = new Expression[len];
            varArgs.toArray(args);
            varArgs = null;
        } else {
            int len = args.length;
            if (len > 0 && args[len - 1] == null) {
                throw DbException.get(ErrorCode.INVALID_PARAMETER_COUNT_2, info.name, "" + len);
            }
        }
    }

    public void setDataType(Column col) {
        dataType = col.getType();
        precision = col.getPrecision();
        displaySize = col.getDisplaySize();
        scale = col.getScale();
    }

    @Override
    public Expression optimize(ServerSession session) {
        boolean allConst = info.deterministic;
        for (int i = 0; i < args.length; i++) {
            Expression e = args[i].optimize(session);
            args[i] = e;
            if (!e.isConstant()) {
                allConst = false;
            }
        }
        int t, s, d;
        long p;
        Expression p0 = args.length < 1 ? null : args[0];
        switch (info.type) {
        case IFNULL:
        case NULLIF:
        case COALESCE:
        case LEAST:
        case GREATEST:
        case DECODE: {
            t = Value.UNKNOWN;
            s = 0;
            p = 0;
            d = 0;
            int i = 0;
            for (Expression e : args) {
                if (info.type == DECODE) {
                    if (i < 2 || ((i % 2 == 1) && (i != args.length - 1))) {
                        // decode(a, b, whenB)
                        // decode(a, b, whenB, else)
                        // decode(a, b, whenB, c, whenC)
                        // decode(a, b, whenB, c, whenC, end)
                        i++;
                        continue;
                    }
                }
                if (e != ValueExpression.getNull()) {
                    int type = e.getType();
                    if (type != Value.UNKNOWN && type != Value.NULL) {
                        t = Value.getHigherOrder(t, type);
                        s = Math.max(s, e.getScale());
                        p = Math.max(p, e.getPrecision());
                        d = Math.max(d, e.getDisplaySize());
                    }
                }
                i++;
            }
            if (t == Value.UNKNOWN) {
                t = Value.STRING;
                s = 0;
                p = Integer.MAX_VALUE;
                d = Integer.MAX_VALUE;
            }
            break;
        }
        case CASEWHEN:
            t = Value.getHigherOrder(args[1].getType(), args[2].getType());
            p = Math.max(args[1].getPrecision(), args[2].getPrecision());
            d = Math.max(args[1].getDisplaySize(), args[2].getDisplaySize());
            s = Math.max(args[1].getScale(), args[2].getScale());
            break;
        case NVL2:
            switch (args[1].getType()) {
            case Value.STRING:
            case Value.CLOB:
            case Value.STRING_FIXED:
            case Value.STRING_IGNORECASE:
                t = args[1].getType();
                break;
            default:
                t = Value.getHigherOrder(args[1].getType(), args[2].getType());
                break;
            }
            p = Math.max(args[1].getPrecision(), args[2].getPrecision());
            d = Math.max(args[1].getDisplaySize(), args[2].getDisplaySize());
            s = Math.max(args[1].getScale(), args[2].getScale());
            break;
        case CAST:
        case CONVERT:
        case TRUNCATE_VALUE:
            // data type, precision and scale is already set
            t = dataType;
            p = precision;
            s = scale;
            d = displaySize;
            break;
        case TRUNCATE:
            t = p0.getType();
            s = p0.getScale();
            p = p0.getPrecision();
            d = p0.getDisplaySize();
            if (t == Value.NULL) {
                t = Value.INT;
                p = ValueInt.PRECISION;
                d = ValueInt.DISPLAY_SIZE;
                s = 0;
            } else if (t == Value.TIMESTAMP) {
                t = Value.DATE;
                p = ValueDate.PRECISION;
                s = 0;
                d = ValueDate.DISPLAY_SIZE;
            }
            break;
        case ABS:
        case FLOOR:
        case RADIANS:
        case ROUND:
        case POWER:
            t = p0.getType();
            s = p0.getScale();
            p = p0.getPrecision();
            d = p0.getDisplaySize();
            if (t == Value.NULL) {
                t = Value.INT;
                p = ValueInt.PRECISION;
                d = ValueInt.DISPLAY_SIZE;
                s = 0;
            }
            break;
        case SET: {
            Expression p1 = args[1];
            t = p1.getType();
            p = p1.getPrecision();
            s = p1.getScale();
            d = p1.getDisplaySize();
            if (!(p0 instanceof Variable)) {
                throw DbException.get(ErrorCode.CAN_ONLY_ASSIGN_TO_VARIABLE_1, p0.getSQL());
            }
            break;
        }
        case FILE_READ: {
            if (args.length == 1) {
                t = Value.BLOB;
            } else {
                t = Value.CLOB;
            }
            p = Integer.MAX_VALUE;
            s = 0;
            d = Integer.MAX_VALUE;
            break;
        }
        case SUBSTRING:
        case SUBSTR: {
            t = info.dataType;
            p = args[0].getPrecision();
            s = 0;
            if (args[1].isConstant()) {
                // if only two arguments are used,
                // subtract offset from first argument length
                p -= args[1].getValue(session).getLong() - 1;
            }
            if (args.length == 3 && args[2].isConstant()) {
                // if the third argument is constant it is at most this value
                p = Math.min(p, args[2].getValue(session).getLong());
            }
            p = Math.max(0, p);
            d = MathUtils.convertLongToInt(p);
            break;
        }
        default:
            t = info.dataType;
            DataType type = DataType.getDataType(t);
            p = PRECISION_UNKNOWN;
            d = 0;
            s = type.defaultScale;
        }
        dataType = t;
        precision = p;
        scale = s;
        displaySize = d;
        if (allConst) {
            Value v = getValue(session);
            if (v == ValueNull.INSTANCE) {
                if (info.type == CAST || info.type == CONVERT) {
                    return this;
                }
            }
            return ValueExpression.get(v);
        }
        return this;
    }

    @Override
    public void setEvaluatable(TableFilter tableFilter, boolean b) {
        for (Expression e : args) {
            if (e != null) {
                e.setEvaluatable(tableFilter, b);
            }
        }
    }

    @Override
    public int getScale() {
        return scale;
    }

    @Override
    public long getPrecision() {
        if (precision == PRECISION_UNKNOWN) {
            calculatePrecisionAndDisplaySize();
        }
        return precision;
    }

    @Override
    public int getDisplaySize() {
        if (precision == PRECISION_UNKNOWN) {
            calculatePrecisionAndDisplaySize();
        }
        return displaySize;
    }

    private void calculatePrecisionAndDisplaySize() {
        switch (info.type) {
        case ENCRYPT:
        case DECRYPT:
            precision = args[2].getPrecision();
            displaySize = args[2].getDisplaySize();
            break;
        case COMPRESS:
            precision = args[0].getPrecision();
            displaySize = args[0].getDisplaySize();
            break;
        case CHAR:
            precision = 1;
            displaySize = 1;
            break;
        case CONCAT:
            precision = 0;
            displaySize = 0;
            for (Expression e : args) {
                precision += e.getPrecision();
                displaySize = MathUtils.convertLongToInt((long) displaySize + e.getDisplaySize());
                if (precision < 0) {
                    precision = Long.MAX_VALUE;
                }
            }
            break;
        case HEXTORAW:
            precision = (args[0].getPrecision() + 3) / 4;
            displaySize = MathUtils.convertLongToInt(precision);
            break;
        case LCASE:
        case LTRIM:
        case RIGHT:
        case RTRIM:
        case UCASE:
        case LOWER:
        case UPPER:
        case TRIM:
        case STRINGDECODE:
        case UTF8TOSTRING:
        case TRUNCATE:
            precision = args[0].getPrecision();
            displaySize = args[0].getDisplaySize();
            break;
        case RAWTOHEX:
            precision = args[0].getPrecision() * 4;
            displaySize = MathUtils.convertLongToInt(precision);
            break;
        case SOUNDEX:
            precision = 4;
            displaySize = (int) precision;
            break;
        case DAY_NAME:
        case MONTH_NAME:
            // day and month names may be long in some languages
            precision = 20;
            displaySize = (int) precision;
            break;
        default:
            DataType type = DataType.getDataType(dataType);
            precision = type.defaultPrecision;
            displaySize = type.defaultDisplaySize;
        }
    }

    @Override
    public String getSQL(boolean isDistributed) {
        StatementBuilder buff = new StatementBuilder(info.name);
        buff.append('(');
        switch (info.type) {
        case CAST: {
            buff.append(args[0].getSQL(isDistributed)).append(" AS ")
                    .append(new Column(null, dataType, precision, scale, displaySize).getCreateSQL());
            break;
        }
        case CONVERT: {
            buff.append(args[0].getSQL(isDistributed)).append(',')
                    .append(new Column(null, dataType, precision, scale, displaySize).getCreateSQL());
            break;
        }
        case EXTRACT: {
            ValueString v = (ValueString) ((ValueExpression) args[0]).getValue(null);
            buff.append(v.getString()).append(" FROM ").append(args[1].getSQL(isDistributed));
            break;
        }
        default: {
            for (Expression e : args) {
                buff.appendExceptFirst(", ");
                buff.append(e.getSQL(isDistributed));
            }
        }
        }
        return buff.append(')').toString();
    }

    @Override
    public void updateAggregate(ServerSession session) {
        for (Expression e : args) {
            if (e != null) {
                e.updateAggregate(session);
            }
        }
    }

    public int getFunctionType() {
        return info.type;
    }

    @Override
    public String getName() {
        return info.name;
    }

    @Override
    public ValueResultSet getValueForColumnList(ServerSession session, Expression[] argList) {
        switch (info.type) {
        case CSVREAD: {
            String fileName = argList[0].getValue(session).getString();
            if (fileName == null) {
                throw DbException.get(ErrorCode.PARAMETER_NOT_SET_1, "fileName");
            }
            String columnList = argList.length < 2 ? null : argList[1].getValue(session).getString();
            Csv csv = new Csv();
            String options = argList.length < 3 ? null : argList[2].getValue(session).getString();
            String charset = null;
            if (options != null && options.indexOf('=') >= 0) {
                charset = csv.setOptions(options);
            } else {
                charset = options;
                String fieldSeparatorRead = argList.length < 4 ? null : argList[3].getValue(session).getString();
                String fieldDelimiter = argList.length < 5 ? null : argList[4].getValue(session).getString();
                String escapeCharacter = argList.length < 6 ? null : argList[5].getValue(session).getString();
                setCsvDelimiterEscape(csv, fieldSeparatorRead, fieldDelimiter, escapeCharacter);
            }
            char fieldSeparator = csv.getFieldSeparatorRead();
            String[] columns = StringUtils.arraySplit(columnList, fieldSeparator, true);
            ResultSet rs = null;
            ValueResultSet x;
            try {
                rs = csv.read(fileName, columns, charset);
                x = ValueResultSet.getCopy(rs, 0);
            } catch (SQLException e) {
                throw DbException.convert(e);
            } finally {
                JdbcUtils.closeSilently(rs);
            }
            return x;
        }
        default:
            break;
        }
        return (ValueResultSet) getValueWithArgs(session, argList);
    }

    private static void setCsvDelimiterEscape(Csv csv, String fieldSeparator, String fieldDelimiter,
            String escapeCharacter) {
        if (fieldSeparator != null) {
            csv.setFieldSeparatorWrite(fieldSeparator);
            if (fieldSeparator.length() > 0) {
                char fs = fieldSeparator.charAt(0);
                csv.setFieldSeparatorRead(fs);
            }
        }
        if (fieldDelimiter != null) {
            char fd = fieldDelimiter.length() == 0 ? 0 : fieldDelimiter.charAt(0);
            csv.setFieldDelimiter(fd);
        }
        if (escapeCharacter != null) {
            char ec = escapeCharacter.length() == 0 ? 0 : escapeCharacter.charAt(0);
            csv.setEscapeCharacter(ec);
        }
    }

    @Override
    public Expression[] getArgs() {
        return args;
    }

    @Override
    public boolean isEverything(ExpressionVisitor visitor) {
        for (Expression e : args) {
            if (e != null && !e.isEverything(visitor)) {
                return false;
            }
        }
        switch (visitor.getType()) {
        case ExpressionVisitor.DETERMINISTIC:
        case ExpressionVisitor.QUERY_COMPARABLE:
            return info.deterministic;
        case ExpressionVisitor.EVALUATABLE:
        case ExpressionVisitor.GET_DEPENDENCIES:
        case ExpressionVisitor.INDEPENDENT:
        case ExpressionVisitor.NOT_FROM_RESOLVER:
        case ExpressionVisitor.OPTIMIZABLE_MIN_MAX_COUNT_ALL:
        case ExpressionVisitor.SET_MAX_DATA_MODIFICATION_ID:
        case ExpressionVisitor.GET_COLUMNS:
            return true;
        default:
            throw DbException.throwInternalError("type=" + visitor.getType());
        }
    }

    @Override
    public int getCost() {
        int cost = 3;
        for (Expression e : args) {
            cost += e.getCost();
        }
        return cost;
    }

    @Override
    public boolean isDeterministic() {
        return info.deterministic;
    }

    @Override
    public boolean isBufferResultSetToLocalTemp() {
        return info.bufferResultSetToLocalTemp;
    }

}
